kgdb broken?

Just booted a -current/amd64 with
options KGDB # remote debugger
options KGDB_DEVNAME="\"com\"",KGDB_DEVADDR=0x3f8,KGDB_DEVRATE=115200
and "boot -d". It seems the "-d" doesn't happen - successful boot without
dropping into the debugger...
Is kgdb known to be working?
Cheers,
Patrick